Can someone please explain the difference between these two concepts? I'd guess that association is generally weaker than correlation, but is there some hard and fast rule that separates the two concept? Is correlation always linear? I feel like I've heard the phrase, "non-linear correlation" ...
I'm not sure the specifics really matter, I'm just asking for my own edification. I'm reviewing PT69, S1, Q24 if that makes any difference.
Thanks!